md-cluster: fix NULL pointer dereference in process_metadata_update
The function process_metadata_update() blindly dereferences the 'thread'
pointer (acquired via rcu_dereference_protected) within the wait_event()
macro.
While the code comment states "daemon thread must exist", there is a valid
race condition window during the MD array startup sequence (md_run):
1. bitmap_load() is called, which invokes md_cluster_ops->join().
2. join() starts the "cluster_recv" thread (recv_daemon).
3. At this point, recv_daemon is active and processing messages.
4. However, mddev->thread (the main MD thread) is not initialized until
later in md_run().
If a METADATA_UPDATED message is received from a remote node during this
specific window, process_metadata_update() will be called while
mddev->thread is still NULL, leading to a kernel panic.
To fix this, we must validate the 'thread' pointer. If it is NULL, we
release the held lock (no_new_dev_lockres) and return early, safely
ignoring the update request as the array is not yet fully ready to
process it.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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Solution
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Workaround
No workaround given by the vendor.
Wed, 06 May 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-362 CWE-476 |
Wed, 06 May 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: md-cluster: fix NULL pointer dereference in process_metadata_update The function process_metadata_update() blindly dereferences the 'thread' pointer (acquired via rcu_dereference_protected) within the wait_event() macro. While the code comment states "daemon thread must exist", there is a valid race condition window during the MD array startup sequence (md_run): 1. bitmap_load() is called, which invokes md_cluster_ops->join(). 2. join() starts the "cluster_recv" thread (recv_daemon). 3. At this point, recv_daemon is active and processing messages. 4. However, mddev->thread (the main MD thread) is not initialized until later in md_run(). If a METADATA_UPDATED message is received from a remote node during this specific window, process_metadata_update() will be called while mddev->thread is still NULL, leading to a kernel panic. To fix this, we must validate the 'thread' pointer. If it is NULL, we release the held lock (no_new_dev_lockres) and return early, safely ignoring the update request as the array is not yet fully ready to process it. | |
| Title | md-cluster: fix NULL pointer dereference in process_metadata_update | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-06T11:28:55.507Z
Reserved: 2026-05-01T14:12:55.998Z
Link: CVE-2026-43271
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-05-06T12:16:48.313
Modified: 2026-05-06T13:07:51.607
Link: CVE-2026-43271
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-05-06T15:15:09Z